The Spokane occurrence is hosted by quartzites, hornblende schists and siliceous limestones of the Mississippian-Pennsylvanian Milford Group intruded by some lamprophyre dykes or sills, less than 2.5 metres thick, that closely conform to bedding and foliation.

The deposit consists of two subparallel veins, that conform to bedding and foliation. The two veins are less than 2 metres apart, they merge and split locally. They are offset by small senestral or dextral northwestern cross-faults. A gouge and breccia band less than 7 metres thick, commonly occurs along the western vein. The ore occurs as lenses scattered along the vein or at the intersection of the northwest cross-faults. The ore consists of massive cubic to fine-grained and sheared galena with some sphalerite in a massive to porous gangue of quartz. Fragments of quartzite occurs in the vein.

Located on the Munn Creek slope, about 4.8 kilometres by road from Ainsworth, the claims lie in a north-west trending line across the southwest corner of the Ainsworth townsite. Both claims were Crown-granted to the Pacific Bullion M. Co. in 1893. The owners worked the property from 1888 to 1896 and from 1915 through 1920. Leasers operated the mine from 1921 to 1929.

By 1920 the deposit had been developed by two adit levels. The upper level, at an elevation 61 metres below the outcrop, was driven for over 274 metres along the vein. Over 122 metres of this was in an oreshoot that was stoped through to the surface. The lover adit was started not far from the portal of the upper and only 8 metres vertically below it, and driven for 110 metres on the fissure. The last 67 metres of this tunnel was on the main ore zone and 55 metres of this part of the drift has been stoped through to the level above.

The Maestro Silver Lead Mines Ltd. was formed in 1937 to develop the Maestro and Spokane mines but no work was done, and the company became defunct in 1940. Ainsworth Vines Ltd., formed in 1936 to operate the Banker mine, gained control of the Spokane and development work was resumed in 1941.

In 1942 Ainsmore Mines Ltd. (later Ainsmore Consolidated Mines Ltd.) was formed to operate the Spokane. A shaft was sunk from the lower adit for 30 metres and from this new level 22 metres of drift and a raise were put in.

Yale Lead & Zinc Mines Ltd. acquired the property in 1949 and leasers worked the mine intermittently through 1957.